Why does a certain maker fit tapered pins to cylindrical holes?

[blindboyjimi]

The guitars are supposed to have final set-up done by the dealer, but with 80,000 guitars sold and many sold on-line that is no longer possible to police. The better dealers used to set up the guitars for the individual buyer as they historically came with higher Bluegrass action. Now they go through a PLEK so it’s less likely the dealers will set-up the guitar for each buyer. It’s a shame but nothing 3 minutes with a good 5 degree reamer won’t solve. I put solid pins in all my guitars so having the 5 degree reamer is a nice tool.

[charles Tauber]

Originally Posted by Taylor Ham

I guess Gauging / the whole tapered hole idea could be more of an issue if Martin uses a bridge with a radius top AND 5 degree pins, which they do. The extra thickness in the center means that by the time the bridge plate is holed thru, the hole is too small to pass a ball end. It's less of an issue with 3 degree pins, but still an effect.

This is a non-issue.

What many luthiers do is to put a piece of masking tape around the circumference of their tapered reamer. They ream until the tape just touches the top edge of the hole, providing consistent, repeatable diameter and taper.

The amount of wood removed is very small, typically about two or three rotations of the reamer. It takes 30 seconds per pin hole, if the appropriate size drill is used.

Where it is more of an issue is with pins of natural materials (e.g. wood, bone....) that can vary in diameter from one pin to the next.

[Scotso]

Originally Posted by JayBee1404

Cost. Pure and simple. It’s cheaper to simply straight-drill six holes and drop in a slotted pin than it is to drill six smaller holes, ream them to the correct size and taper for solid pins to fit correctly, and carefully cut correctly-sized string-slots in the holes.

The usual disclaimers apply......IMHO, YMMV etc.

MMMM...I do not buy that. I am sure CNC could drill tapered and straight holes with the same accuracy at the same price. This is not a hard procedure

[JayBee1404]

Originally Posted by Scotso

MMMM...I do not buy that. I am sure CNC could drill tapered and straight holes with the same accuracy at the same price. This is not a hard procedure

Perhaps so, but the pins would still not be properly fitted to the holes, and that would still need to be done by hand using a tapered reamer. On another site several years ago, a contributor reported that, on a factory tour, they had asked the guide why the company had originally stopped tapering and slotting the pin-holes and started straight-drilling the holes and using slotted pins. The answer the guide gave was (and I’m summarising here), “Time and cost savings”.

Sounds pretty unequivocal to me.

[lar]

and don't forget, this is how they make end pins too.

Sigh!

[dnf777]

A few thoughts...
1). It works fine as is.
2) keeps cost and production time down.
3) bridge plates are doing just fine with a little care
4) for their intended function, no need for high-tolerance tapered fit. In fact, could make string change MUCH more difficult! Dont want to need a puller and mallet to remove pins!
5) ever give one too many twists on a reamer? Not an easy remedy for that one.

[charles Tauber]

Originally Posted by dnf777

1). It works fine as is....

3) bridge plates are doing just fine with a little care

That raises an interesting question. When should one eliminate "best practice" as defined by decades - or more - of established practice?

For example, another large American guitar manufacturer has taken to making guitars with backs and sides of flat-sawn black walnut. Why? Not because black walnut is scarce or difficult to obtain quarter sawn. Given that quarter sawn materials for tops, backs and sides have a long established history of use in instrument making, what is the rational for abandoning it?

Flat sawn walnut "works fine as is" and is "doing just fine with a little care"? Might be, might not be. As with bridge plate wear, it will be interesting to see if splitting backs and sides of flat sawn walnut become "common".

5) ever give one too many twists on a reamer? Not an easy remedy for that one.

A very easy remedy for that: line the hole with a thin film of CA glue, re-ream. Takes about 2 minutes.

[A Wolf]

As has been mentioned, the machine time for a tapered hole and a straight hole is identical—assuming an automated machine in drilling. Each tapered hole would be “identical.” Since the manufacturer uses injection molded pins, these are also close enough to identical to mean that no “final set-up hand reaming” would need to be done.

It’s not as if the borer lines up each hole and an operator pulls a lever to a set point. Or at least, it better not be, in 2021, for anyone that’s turning out hundreds of whatevers in a day.

Tapered bits do cost substantially more than straight bits though. But even in ebony, a tool steel bit (not to mention carbide) would last through several hundred bridges before needing either replacement or sharpening. (Until I recently retired I owned a prototype shop, so am very familiar with tooling, spray booths, etc. Part of my 40 years of doing this also involved helping companies modify their designs and processes to allow for large scale manufacturing.)

[rstaight]

Originally Posted by A Wolf

Tapered bits do cost substantially more than straight bits though. But even in ebony, a tool steel bit (not to mention carbide) would last through several hundred bridges before needing either replacement or sharpening. (Until I recently retired I owned a prototype shop, so am very familiar with tooling, spray booths, etc. Part of my 40 years of doing this also involved helping companies modify their designs and processes to allow for large scale manufacturing.)

I am a manufacturing engineer and I work with aluminum castings. I would expect a carbide drill to last at least 5,000 to 10,000 pieces. A PCD (diamond) tool to last 120,000.

So with wood I would expect to change every couple of months. Just because of the principle of it. Cost is not that great.

[UncleJesse]

Originally Posted by dnf777

A few thoughts...
1). It works fine as is.
2) keeps cost and production time down.
3) bridge plates are doing just fine with a little care
4) for their intended function, no need for high-tolerance tapered fit. In fact, could make string change MUCH more difficult! Dont want to need a puller and mallet to remove pins!
5) ever give one too many twists on a reamer? Not an easy remedy for that one.

I don't think it works fine as it is. Often times it's easy to get a string not properly seated against the bridge plate because the slotted pins and string together are too big for the hole which causes the pins to ride too high. Once you've reamed and slotted a guitar you realize just how easy it is to do at home. It makes string changes easier, it makes the pins sit better, and it keeps your bridge plate in great shape. There's really no downside at all.

[JayBee1404]

Originally Posted by UncleJesse

I don't think it works fine as it is. Often times it's easy to get a string not properly seated against the bridge plate because the slotted pins and string together are too big for the hole which causes the pins to ride too high. Once you've reamed and slotted a guitar you realize just how easy it is to do at home. It makes string changes easier, it makes the pins sit better, and it keeps your bridge plate in great shape. There's really no downside at all.

^^^^^^
Yep, THIS!

[tadol]

Its purely a question of caring - if the “luthiers” on the assembly line cared, they’d work with management to figure this out, and even if there were some tiny increase in cost, it would indicate the pride and concern they had for their product. But maybe the accountants and management have final say in product quality and techniques allowed in their craftsmanship, basic cost vs quality, which should make you wonder where else they’ve cut corners -

We had tapered drill bits with stop collars made by Fuller decades ago for accurately sizing holes for wood screws - it ain’t rocket science -

[rstaight]

Originally Posted by tadol

Its purely a question of caring - if the “luthiers” on the assembly line cared, they’d work with management to figure this out, and even if there were some tiny increase in cost, it would indicate the pride and concern they had for their product. But maybe the accountants and management have final say in product quality and techniques allowed in their craftsmanship, basic cost vs quality, which should make you wonder where else they’ve cut corners -
-

A "certain" manufacture has had issues with binding coming off in recent years.

[gmel555]

I'm willing to admit -if need be- that I'm just "unaware", but I've been playing for 50 years and have had at least one guitar in my possession from "that certain builder" at all times during that period. I can't recall an issue with the pins or bridge, except a '73 D-18 that had the bridge misplaced...maybe I've just been otherwise lucky? I'm also not a "certain builder can do no wrong" person either but I'm feeling kinda in the dark on this.

[Taylor Ham]

Hey, if it's functionally identical then it's all the same to me. It just seemed odd that someone with the reputation that Martin has would make this design decision. I think it's not reason enough to avoid buying one, and there are good reasons why they are considered the benchmark, but I think this is one small aspect where they can live up to their well earned reputation better. I would pay the extra labor to have this part also handmade, from the factory.